Intro to Diatonic Harmony

When speaking of music and harmony, you will frequently encounter the term diatonic. It’s important to understand its meaning. You’ll be applying this concept all of the time whether you realize it or not.

What Does “Diatonic” Mean?

The Greek prefix “dia-“ means through, or across (as in the words ‘diameter’ and ‘diagonal’). As I said in keys in music, the tonic is a key’s center. Diatonic means through a tonal center, or across the notes of a key.

When we use the musical term diatonic, we mean the notes being used all come from the key. In that way the terms diatonic and key mean much the same thing.

For instance, the key of C major contains the seven notes of the C major scale  C, D, E, F, G, A, and B. Any music said to be diatonic and in the key of C only uses combinations of those 7 notes from C major.

If a melody is said to be diatonic and in the key of C, it only uses the 7 notes of the C major scale/key.

If a chord progression is said to be diatonic and in the key of C, all of the notes used to build the chords would come from the notes of the key of C major. So, an F major triad would be a diatonic chord in the key of C because F major contains the notes F, A, and C  all notes within the key. An F minor triad contains the notes F, Ab, and C. Since the key of C does not contain an Ab, F minor is not a diatonic chord in the key of C.

Diatonic Harmony and Music

A lot of music is purely diatonic. Purely diatonic music has a simple, straightforward sound to it. For instance folk songs and nursery rhymes are often strictly diatonic.

More often, songs are mostly diatonic only straying from the notes of the key once in a while.

In order to fully understand music containing non-diatonic notes, you first need to understand basic diatonic harmony. Diatonic harmony is the study of how notes within a key relate to one another.

In Summary

This lesson is just to give you a quick introduction to the concept of diatonicism. In the coming harmony lessons we’ll start to apply the concept so you gain a working knowledge of simple diatonic harmony.